As the population ages, rates of cancers, cardiac diseases, and cerebral vascular diseases continue to increase year by year. A common symptom of these diseases is “hypoxia” accompanied by failure of blood circulation. It is thought that reliable and sensitive detection of abnormal hypoxic symptoms hidden in vivo would not only lead to early detection of these three major diseases but also contribute to early treatment and development of novel treatments.
As such an example, Patent Literature 1 discloses a method for diagnosing a patient's tumor hypoxia including detecting the level of osteopontin (OPN) in a patient's body fluid and comparing the level with a predetermined value.
Hypoxia-induced gene 1 (HIG-1) was reported in 2000 as one of the genes induced under hypoxic conditions (Non-patent Literature 1). HIG-1 is induced also by a decrease in glucose concentration. HIG-1 is considered to be localized in an inner membrane of mitochondria and to have a function of inhibiting hypoxia-induced cell death; however, the details thereof have yet to be revealed. Patent Literature 2 and 3 also disclose the base sequences of hypoxia-induced genes HIG-1 and HIG-2, and the encoding polypeptide sequences.
Regarding a method for analyzing a HIG-1 molecule using an antibody, there has been no example of using a monoclonal antibody, and there is only a report indicating that analysis was performed using a rabbit antiserum in 2006 (Non-patent Literature 2). However, since it is difficult to stably supply a certain grade of antibody with such a polyclonal antibody, and nonspecific antibodies are included in a large amount, a detailed analysis at a molecular level is limited.
Further, neither Patent Literature 2 nor 3 discloses an example in which a monoclonal antibody against a human HIG-1 polypeptide is actually obtained.
Therefore, to solve the above problem, a monoclonal antibody that has a high affinity for a human HIG-1 polypeptide and is specifically reacted with the human HIG-1 polypeptide is desired.